1. Field
Example embodiments of the present general inventive concept relate to an apparatus to dissipate heat, and more particularly, to a heat sink having an enlarged dissipating surface and an improved dissipation capability and an apparatus having the same heat sink.
2. Description of the Related Art
Various recent electronic instruments are electrically connected to a memory module in which a plurality of memory packages is mounted on a printed circuit board (PCB) through at least one electrical connection terminal. The memory package generally includes a plurality of semiconductor chips that is electrically connected to an external electric circuit by a packaging process.
When the memory package including the semiconductor chips is electrically operated for a long time, the semiconductor chip generally has a high temperature due to heat caused by the electric power that is consumed in the semiconductor chip. High chip temperature usually causes reliability deterioration of the individual semiconductor chip. The reliability deterioration of each semiconductor chip finally results in an operational failure of the electronic instrument including the memory module that is composed of the semiconductor chips.
For that reason, heat dissipation from each of the semiconductor chips has been a significant factor for increasing electrical reliability of the memory package and the memory module. Particularly, various research on the heat dissipation from the memory module have been intensively carried out in accordance with recent technical trends in a semiconductor device such as a substrate with a small-size, high-integration degree, high operation speed and light and thin characteristics. As a result of the research, a fin-type heat sink has been suggested and widely used for improving the heat dissipation of the chip in which a plurality of fins is located on or over a heat source such as the semiconductor chip. The fin on the heat source enlarges a surface area as much as possible through which the heat generated from the chip is transferred to surroundings.
FIG. 1 is a perspective view illustrating a conventional fin-type heat sink 90 for dissipating heat from a memory module.
Referring to FIG. 1, the conventional fin-type heat sink 90 includes a pair of base plates 10, and each of the plates 10 includes a first surface 10a to which a contact pad having an excellent thermal conductivity is adhered and a second surface 10b opposite to the first surface 10a and to which a plurality of dissipating fins 12 are mounted.
The contact pad makes physical contact with an upper portion of a memory package located in the memory module M and absorbs the heat from the memory package in operating the memory module M. The plurality of the dissipation fins 12 protrudes from the second surface 10b by a predetermined height and is integrally formed together with the base plate 10 in one body at a predetermined gap distance. That is, the dissipation fins 12 are spaced apart from each other by a gap distance in a first direction I and extend in a second direction II to be disposed in parallel with each other. Each of the dissipating fins 12 has a length L much greater than a width w, and thus has a sufficiently large surface area S. The dissipation fins 12 also have a height from the base plate 10 in a third direction III.
The heat in the memory module is sufficiently transferred to the base plate 10 due to the excellent thermal conductivity of the contact pad and is rapidly dissipated to the surroundings due to the sufficiently large surface area of the dissipating fins 12. The efficiency of the heat dissipation is determined by the surface area S of the dissipation fin 12 as well as the thermal conductivity of the contact pad.
In general, the pair of the base plates 10 makes contact with an upper surface and a lower surface of the memory module M, respectively, and each of the base plates 10 is individually located on the upper and lower surfaces of the memory module M. Therefore, a coupling unit 20 is provided to fix the individual dissipating fin 12 to the upper and lower surfaces of the memory module M to thereby form a pair of the base plates 10 coupling with each other.
A clip having a great elastic coefficient is usually used as the coupling unit 20. For example, the clip is formed into a general U-shape and includes a clipping portion 22 making contact with the second surface 10b of each base plate 10 and a body 24 connected to the clipping portion 22.
The dissipation fin 12 is partially removed from the second surface 10b of the base plate 10 along the second direction II such that the dissipating fins 12 are discontinued on the base plate 10 and spaced-apart from each other in the second direction II, to thereby form a clip area 14 on the second surface 10b of the base plate 10 to accommodate the clipping portion 22 of the clip 20. The clip area 14 is formed on the second surfaces 10b of each base plate 10, respectively, and the clipping portion 22 of the clip 20 is located at each of the clip areas 14, so that each of the base plates 10 make contact with the upper and lower surfaces of the memory module M, respectively, by the clip 20.
However, the above conventional fin-type heat sink 90 has a problem in that the dissipating fin 12 corresponding to the clipping area 14 is removed from the second surface 10b of the base plate 10 to thereby reduce the efficiency of the heat dissipation.
The dissipating fins 12 corresponding to the clipping area 14 are removed from the second surface 10b along the first direction I, and thus the surface areas of the dissipating fins 12 are diminished due to the removed portions of the dissipating fins 12. In addition, the clipping area 14 is located on the second surface 10b of the base plate 10 at both of the upper and lower surfaces of the memory module M, and thus the loss of the surface area is significantly increased in the conventional fin-type heat sink 90. A recent electronic instrument generally has a longer memory module and thus requires more clips for clipping the base plates 10 to the long memory module, and thus the surface area of the dissipating fin may be decreased by geometric progression in the fin-type heat sink.
Accordingly, there is still a need for an improved fin-type heat sink for optimizing the efficiency of the heat dissipation. When the memory module is used in a server unit for a computer system, the efficiency of the heat dissipation becomes more important because of poor air circulation in the server unit.